(1) Field of the Invention
The present invention generally relates to a digital data recording apparatus, and more particularly to a digital data recording apparatus adapted for recording digital audio signals in different areas of a recording medium and for reproducing audio signals from the recording medium.
(2) Description of the Related Art
Recently, the recording of audio signals such as music sound in a recording medium such as a compact disk is made by using multitrack digital audio data recording technology. A multitrack digital audio tape recorder is desirable because it can record audio signals in a recording medium and can reproduce audio signals from the recording medium with no significant deterioration of sound quality if the dubbing is repeated. There is an increasing need for a compact, less expensive multitrack digital audio tape recorder for personal or home uses.
Conventional 16-track, 32-track, 48-track or 64-track digital audio tape recorders have been commonly used in recording studios or the like. It is necessary for the conventional recorders mentioned above to use a magnetic tape having a large width in which a plurality of tracks extending in parallel to the longitudinal direction of the tape are formed to record audio signals. For this reason, the above conventional recorders will become a large scale system and will be expensive. Also, in the above multitrack digital audio tape recorders, it is difficult to increase the speed of reading and writing audio signals from and to the magnetic tape.
In order to increase the speed of reading and writing, an improved multitrack digital data recording method has been proposed. In the improved recording method mentioned above, a plurality of tracks extending obliquely to the longitudinal direction of a magnetic tape are formed for a higher recording density and a speedier reading and writing. However, when the improved recording method is applied to a multitrack digital audio tape recorder, it is necessary to use a large-scale time base corrector for enabling a higher recording density on a recording medium. Thus, there is a problem in that the multitrack digital tape recorder using such a time base corrector will become bulky and expensive.
A conceivable method for constructing a less expensive, compact multitrack digital audio tape recorder is to make use of a mechanical deck of 8 mm video tape recorder (VTR) and an integrated signal processor of rotary digital audio tape recorder (RDAT). The 8 mm VTRs are widely prevailing in recent years since they are compact and of light weight. The mechanical deck of 8 mm VTR includes a rotary drum, a tape running system and a tape cassette loading/unloading mechanism. However, when the 8 mm VTR mechanical deck and the RDAT integrated signal processor are combined, there are four major difficulties which should be resolved: (1) tracking signal, (2) audio signal processing method, (3) tape format and (4) circuit size.
The four major difficulties mentioned above will be described in the following: (1) The automatic track finding (ATF) method of RDAT recorder is greatly dependent on the format of magnetic tape. However, the automatic track finding (ATF) signals of 8 mm VTR recorder are recorded as analog signals. (2) The RDAT integrated signal processor is designed to process two-channel digital audio signals. This signal processing method is different from the signal processing method of 8 mm VTR recorder. (3) In order to process multichannel digital audio signals by combining a plurality of RDAT integrated signal processors each of which is designed to process two-channel digital audio signals, it is necessary to add a large amount of redundant bits to the processed signals for error correction. Therefore, it is difficult to achieve a higher recording density on the recording medium. (4) The RDAT recorder is designed to record two-channel digital audio signals in a magnetic tape and the magnetic tape is wound on a rotary drum by 90 degrees. However, in a case of the 8 mm VTR recorder, it is necessary to record 8-channel video signals in a video tape, and the video tape is wound on a rotary drum by 226 degrees. Therefore, it is necessary to make use of a large-scale time base corrector, in order to resolve the problems when the 8 mm VTR mechanical deck and the RDAT integrated signal processor are combined.
For example, FIG. 1 shows a conventional multitrack digital audio tape recorder using a known large-scale time base correcting circuit. In FIG. 1, there are shown an integrated signal processing circuit 100 of rotary digital audio tape recorder (RDAT), a mechanical deck 200 of 8 mm video tape recorder (VTR) including a rotary drum 220 with magnetic heads 210, and a time base corrector (TBC) 300.
In the time base corrector 300 shown in FIG. 1, a static random access memory (SRAM) 310, a writing counter 320, a reading counter 325, and an arbiter 330 are provided. The arbiter 330 functions to prevent the interference between the writing of information to the SRAM 310 and the reading of information from the SRAM 310. As shown in FIG. 1, the TBC 300 must be made up of various circuit components, and there is a problem in that the time base corrector provided in the multitrack digital audio tape recorder will be bulky and expensive.